Rock drill

Abstract

A rock drill for rotary hammers is proposed in which a conveying helix ( 3 ) having main and secondary webs ( 6 to 9 ) is used. A one-piece carbide crown, with its wing-shaped main and secondary lips ( 24 to 27 ), is butt-welded to the conveying helix.

1. A rock drill having a longitudinal axis, the rock drill comprising:
 a drill head formed from a one-piece carbide crown, the drill head having 
 main lips having a first outside lip diameter formed by a longitudinal extent of the main lips, and  
 secondary lips having a second outside lip diameter formed by a longitudinal extent of the secondary lips and being set back relative to the first outside lip diameter; and  
 
 one of a single- and multi-state conveying helix having 
 helically encircling main webs having a first outside web diameter that is equal to or slightly smaller than the first outside lip diameter, and  
 helically encircling secondary webs having a second outside web diameter, 
 the main and secondary webs having conveying edges in disposal flutes for transporting drillings,  
 
 the conveying helix being connected to the drill head by one of a welded or brazed joint in such a manner that the main webs are connected to the main lips and the secondary webs are connected to the secondary lips.  
 
 
   
   
     2. The rock drill according to  claim 1 , wherein the conveying edges of the main and secondary disposal flutes run out into lateral front flanks of the main and secondary lips of the carbide crown drill head. 
   
   
     3. The rock drill according to  claim 1 , wherein the first and second outside lip diameters are one of the same size as and slightly larger than the first and second outside web diameters, respectively. 
   
   
     4. The rock drill according to  claim 1 , wherein the main and secondary lips form one of a cross shape and X-shape in plan view. 
   
   
     5. The rock drill according to  claim 1 , wherein the carbide crown of the drill head has one of a centering point and at least one or more centering lips. 
   
   
     6. The rock drill according to  claim 1 , wherein the conveying helix is of a two-start design, having two helically encircling main webs and two secondary webs lying in between in each case. 
   
   
     7. The rock drill according to  claim 1 , wherein the first outside lip diameter is larger than the second outside lip diameter, and the second outside lip diameter is approximately 0.5 to 0.9× the first outside lip diameter. 
   
   
     8. The rock drill according to  claim 1 , wherein a thickness of the main lips is one of approximately the same width as, slightly wider than and slightly narrower than a land width of the main webs. 
   
   
     9. The rock drill according to  claim 1 , wherein the secondary webs have a land tapering to a point. 
   
   
     10. The rock drill according to  claim 1 , wherein the secondary webs have a land tapering to one of a point, a flat end, and a round end, and the secondary webs have a prominence relative to a flute root, the prominence being one of rectangular, trapezoidal, semi-trapezoidal, triangular, crowned, and hemispherical in cross section. 
   
   
     11. The rock drill according to  claim 1 , wherein, to form bearing surfaces for drillings, the conveying edges of at least one of the main webs and secondary webs run approximately at right angles to the drill longitudinal axis. 
   
   
     12. The rock drill according to  claim 1 , wherein the carbide crown of the drill head has a connecting surface that is substantially flat and has at least one of centering and positioning aids. 
   
   
     13. The rock drill according to  claim 1 , wherein the main and secondary lips have cutting edges arranged in a plane lying perpendicularly to the drill longitudinal axis. 
   
   
     14. The rock drill according to  claim 7 , wherein the second outside lip diameter is 0.7 to 0.8× the first outside lip diameter.